It's been over one hundred years since Alexander Graham Bell uttered those famous words that heralded the beginning of a new era in communications. During that period, the public network supporting telephonic communications, i.e., the Public Switched Telephone Network (PSTN), evolved into a labyrinth of electronic devices or equipment connected by various cable media. The electronic equipment typically includes switches, digital cross connects (DCSs), and multiplexers to name a few. The cable media typically includes copper, coaxial and fiber cable.
The PSTN primarily comprises a circuit switched network. A circuit comprises a path or timeslot through a network for carrying information. In a circuit switched network such as the PSTN, an electronic switch establishes and keeps open a circuit between two or more users, such that the users have exclusive and full use of the circuit until the circuit connection is released. As information a circuit traverses the network it is processed by the electronic equipment that comprise the network, such as, for example, digital cross-connects and multiplexers. In essence, each circuit provides a unique timeslot or path that is reserved for carrying voice or other information between origination and destination points for the duration of a call or service.
In contrast, in a packet switched network, a path is not reserved for carrying information between origination and destination points. Instead, information is placed in packets that include address information typically identifying the originating and destination point of each packet. The address information is usually placed in headers that form a part of each packet. The packets are then received by packet switches, which autonomously route the packet through the network by using routing tables to determine the next hop or destination for a packet. The routing table essentially comprises a look-up table that associates logical or physical ports on a packet switch based on address information in a packet's header.
Packet switching technology continues to rise in popularity and promises to replace the PSTN as the vehicle for supporting the very service that spawned the development of the PSTN—telephony. As packet switching increases in popularity, however, network providers and users are demanding new features to assist in making these networks more robust and reliable. Such features include the ability to test a facility or equipment connected to a packet switched network.
The PSTN, for example, supports functions that allow for testing of a facility or equipment that is part of that network. One test, for example, is called a SPLTE (split equipment). A SPLTE is normally associated with a digital cross connect (DCS) and comprises interrupting a circuit traversing the DCS so that the circuit may be connected to a test set. Once connected to the test set, the circuit is then used to test other equipment residing on the network. In contrast, a SPLTF (split facility) comprises disrupting a circuit so that a facility on the network may be tested. Additional details relating to SPLTE and SPLTF functionality in a DCS are described in Telcordia Technologies, Inc., GR-834-CORE and GR-1402-CORE, the disclosures of which are hereby incorporated herein by reference.
Implementation or emulation of these types of test functions, e.g., SPLTE and/or SPLTF, in a packet switched network present new challenges that need to be addressed. Of utility then are methods and systems for implementing or emulating these and other testing functionalities in packet switched networks.